Thermostat



April 26, 1938. s. VERNE-r THERMOSTAT Filed Jan. 30, 1935 INVENTORATTORNEY Patented Apr'. 26, 1938 UNITED STATES THERMOSTAT SergiusVernet, New York, N. Y., assignor to Vernay Patents Company, Dover,Del., a corporation of Delaware Application January 30, 1935, Serial No.3,999

11 Claims.

This invention relates to new and useful improvements in control devicesand more particularly in thermostats and certain power transmittingmeans particularly adapted for use in connection therewith.

One object of this invention is to provide a new method of preventing orsubstantially minimizing supercooling in devices. employing substanceshaving a crystalline stage in their thermic cycle of operation.

Another object of this invention is to provide eilicient means forrectifying and transmitting power from a pressure responsive means ordiaphragm to a piston or other actuated member.

Further objects and advantages will appear more fully hereinafter.

Referring to the drawing wherein corresponding parts are represented bylike numerals:-

Fig. 1 is a view in vertical central section of a thermostaticallyactuated valve embodying my invention,

Fig. 2 is a detail view in section showing a modied form of the cup orcontainer of Fig. 1,

Fig. 3 is a view in longitudinal central section showing a variantstructure also embodying my invention,

Fig. 4 is a detail sectional view of a porous filter plate,

Fig. 5 is a detail sectional view of a modified x form of pressureresponsive means and comprises a corrugated metallic diaphragm suitablefor use in the structures of the present disclosure.

Fig. 6 is a detail view in longitudinal section of a modified form ofpart of the structure of Fig. 1,

Fig. 'l is a detail view in longitudinal section of a modified form ofpiston, and v Fig. 8 is a detail view in longitudinal central section ofa modified and compact form of cylinder structure.

The thermic motor shown in Fig. 1 comprises a hollow, preferablycylindrical cover or closure member I having an end Wall attached to thecup 2 and preferably rigidly secured thereto by means of the rivets 3.Clamped and sealed at its periphery between the end wall of cover I andthe container or receptacle 2 and sealing the open top of the containerthere is a pressure responsive means such as a flexible diaphragm 4 madeof rubberized fabric or any other suitably treated material orcombination of materials. The cover I has in its end wall a centralrecess or chamber I having its open side facing the diaphragm 4 and iscentrally apertured, as at Ib. Positioned in and extending through theaperture Ib there is a plunger or piston 5 connected to an alined shaft6 by a sleeve nut 1 The shaft 6 is pivotally secured to a valve or vane8, preferably a plate or disc of the buttery type, by a pivot pin 9. Thevane 8 is located in a conduit or' sleeve I0 preferably concentric withshaft 6 and rigidly 5 secured to and in communication with the in-lterior of cover I. Within the recess la there is a spring II, held undercompression between the cover I and piston head 5' of plunger 5, andwhich tends to keep the vane 8 in the fully closed posi- 10 tion. 'I'hevalve or vane 8 is pivotally supported in the wall of sleeve or conduitI0 by bearing means I I, such as trunnions. A crystalline material I3 islocated in the bottom portion of the cup 2, and is contained in thecellular structure 15 of the fins I2 which are preferably formed by acoiled metal ribbon. Overlying the crystalline material and lling thecavities between the separate crystals or groups of crystals' within thefins there is a force transmitting liquid I'I. This liquid also lls thespace in the container 2 between the crystalline material I3 and thediaphragm 4 so that expansion of the material will be transmitted by theliquid to the diaphragm. Porous felt material I4 is located above the n25 structure I2 and is pressed rmly down upon it by the perforated plateI5 which is fixed in position in the container 2 in any suitable manner.

The operation of the device starting from the closed position is asfollows: A rise in temperature of the unit to the fusing point of thecrystalline material I3 will cause the latter to change from the solidto a liquid state with an accompanying change in volume. Materialsexpanding while entering their liquid state such as paradichlorbenzene,paradibrombenzene, cyclohexane, are suitable for this purpose. Theliquid I1 will rst be displaced from the minute spaces between thecrystals. This change in volume will be transmitted by the liquid I1 tothe diaphragm 40 4, which will then be pushed up toward the piston 5. Asthe crystals continue to fuse, the change in volume will become greater,and the liquid I1 Will continue to force the diaphragm 4 against thepiston head 5', moving the piston 5 in a vertical 45 direction andchanging the position of the vane 8. This action will continue until thecrystalline material has entirely fused. 'I'he piston 5 will then havemoved the vane 8 to open position. The boiling points of the crystallineand liquid material used are sufiiciently high to prevent vapor frombeing formed under all operating conditions.

A decrease in temperature sufllcient to .cause the crystallization ofthe material I3 will result in a corresponding change in volume. Thetension of the spring II acting on the piston head i will move the vane8 towards its closed. position. The full crystallization of the materialI3 will allow the diaphragm 4 to recede slightly from the piston head 5to its position,- Fig. 1, after the vane 8 has closed completely. Thisclearance is desirable to eliminate the effects of the slight expansionoccurring in the various materials prior to a change in state.

Crystalline materials serviceable for thermostats are usually poorconductors, and if used in one unbroken mass, cause such lag inoperation as to render the unit impractical for many purposes. The heatconducting fin structure I2 is in thermal contact with the walls of cup2 and acts to rapidly and uniformly conduct external temperature changesto the modifying materials within the unit.

Damage to the diaphragm 4 may be caused by the crystalline material I3coming in contact with it, either through chemical action or by theprevention of its proper flexing due to the crystals tending to formaround its outer edge and upon its surface. The felt material I4 and theperforated disc I5 cooperate to localize the crystalline material I3,thereby preventing it from coming in contact with the diaphragm 4. Otherand additional protective means such for instance as a cupped imperviousauxiliary diaphragm might also be included between the main diaphragm 4and the perforated plate I5. The closely spaced fins I2, by the creationof capillary forces and by their baffling effect, also cooperate tolocalize the crystalline'material I3. It is thus possible to shake oreven tip the unit considerably without displacing the material I3 fromits original position.

Solid solutions or other crystalline substances used as modifyingmaterials vin thermostats of the type described are apt to separate orstratify when repeatedly submitted to temperatures high enough to causeonly their partial fusion. These and other related phenomena modify theoriginal volumetric characteristics of the crystalline materials,thereby affecting the calibration of the thermostat. The use of theshallow cup 2 and the location of the crystalline material I3 in thecapillary chambers and spaces of the iin structure I2 reduce thistendency to a minimum, since the crystalline material I3 is uniformlyheated throughout, and the liquid fraction resulting from partial fusionis retained in its original relation to the remaining crystals by theexertion of capillary forces.

Supercooling of the crystalline materials is here minimized by the useof the felt material I4. A few crystals become lodged in the feltmaterial where they are not so readily subjected to changes intemperature. They therefore are not fused as quickly as the main mass ofcrystals located in the iin structure I2. When the temperature dropssufficiently. they act as nuclei from which crystallization ispropagated throughout the entire mass. Among the cooperating materialsfound useful for minimizing supercooling may be mentioned activatedcharcoal, granulated quartz, and carborundum crystals. In general,initiating crystals having complex, complementary, or correspondingstructures to the materials used, and characterized by a low thermalcoefficient of expansion, are preferred. The choice of initiatingcrystals may be made on one further and important consideration: Whenmodifying crystals of any one type are gradually fused, a transformationof pattern to one tending to persist even in quasi-dissolved state isevidenced. It is this latter pattern which is the more important in theselection of phasechange media, be they crystalline or otherwise. Thedifficulties of accurately determining this persistence pattern areconjoined by the more practical one of actually finding a structure ofthe type required. 'I'he ideal condition obviously rests in utilizingidentical crystals both for motor action and as phase-change media.

Fig. 2 illustrates one structure by which this ideal condition has beensuccessfully obtained. Here, the felt washer I4 and perforated metaldisc 5 of Fig. 1 are replaced by a porous filter plate I5*, see Fig. 4.This filter plate acts to prevent the crystalline material I3 in eitherits liquid or solid form from entering the chamber I1* bounded by saidplate and diaphragm so long as the non-modifying and force transmittingliquid (e. g., water) I1 is also present in the crystal containingchamber Ilb below plate I 5*, but readily permits the passage of suchnon-modifying liquid from the one chamber to the other. At the bottom ofthe crystal chamber, and projecting down from it, there is a tube2\having a bore of cross-section and volume negligibly small compared tothat of the crystal chamber and having its outer end closed and sealed,as lat 2*. After one heating, the material in this tube scgregates, andwith a greater percentage of the high melting point material towards thebottom orouter end 2a, if materials which expand in fusing are used.Upon cooling, and before the normal crystallization range of the mainbulk of material I3 in the fin structure I2 is reached, the material nin the hollow projection 2 crystallizes, thus providing seed crystals topropagate crystallization throughout said mass.

A further application of the principles above set forth is illustratedin Fig. 3. In this modification, a partition or plate 24 separates theheat chamber 24* on the left from the space or chamber 24h on the rightcontaining relatively cool surrounding air. The bushing or supportingmember 23 removably postioned in and closing an aperture 23* in thepartition 24 serves to conveniently install and replace the thermostatunit mounted thereon. 'I'he elongated seed crystal tube or container 2hhas its closed outer end 2 positioned in the cooler section or chamber24D on the right and extends through a bore or aperture in thesupporting bushing 23 in which it is secured by a packing bushing 22. ASince in general the crystals at the sealed end 2 will always remain inthe solid state, when the crystals at the other extremity in the heatchamber 24* have fused, it is clear that there will always exist someintermediate point in the tube whereat crystals having structurescorresponding to their persistence pattern may be found. Thus,phasechange media of the ideal type are here automatically provided, andSupercooling is minimized.

Like the structure of Fig. 2, that in Fig. 3 also utilizes the filterplate I5, This plate may be made from a variety of siliceous and othermaterials; and excellent results have been obtained with one made ofporous bronze, illustrated in Fig. 4, The tube 2b opens at its inner endthrough the side wall of cup 2 in which it is hermetically sealed. Asdescribed above, the cup 2 contains a capillary heat transmittingnstructure I2 which receives the crystalline material I3, the plate I5*serving to hold the material I3 within the structure I2. The cup 2 isalso closed and sealed by the flexible diaphragm 4 which is tightlyclamped at its periphery between a shoulder on cup 2 and a flange on theclosure member In this form of thermostat unit, the member YI 'ispreferably an 'elongated hollow tube which extends through an Beyond thebushing or nut 2| the member Ic is preferably further restrictedinternally to provide a cylinder or piston bore to receive areciprocatory piston 5b. The power factor in piston actuation isimproved by utilizing a plastic material 5 between the diaphragm 4 andpiston 5b. By forming a constricted cylinder as at 5 in the body sectionI so that the area of plastic material or other fluid exposed to thehead of the piston 5b is a fraction ofthat exposed to the diaphragm 4,substantial piston displacement in the operating range is obtained.

In structures employing hydraulic power-` transfer, as described abovein connection with Fig. 3, a corrugated metallic diaphragm 4, such asshown in Fig. 5, preferably with stiff center portion 4', not onlyincreases the effective area and makes for compactness, but also throughit a pistonaction is more closely simulated.

Due to the rather high pressures which may be generated in the hydraulicpower-transfer type of thermostat, even when cylinder and piston havebeen accurately machined, gradual seepage of the plastic may occur. InFig. 6, the body section and. cylinder head Ie corresponding to theclosure member Ic of Fig. 3, has a plurality of ducts 30 exr tendinglongitudinally of the piston 5d and has a plurality of transverseintersecting ducts 3l with end closure plugs 32. The ducts 3|communicating with ducts 30 also intersect the piston cylinder 5e and attheir intersection are provided with annular recesses 33. These ducts 3Uand 3| and recesses 33 are filled with a substance of higher viscositythan the plastic material or fluid 5c, so that the rate of seepage willbe decreased. The body section le is provided with a lateral peripheralflange l' by which it may be clamped and sealed to the cup 2 with theplastic material 5c abutting the diaphragm 4 or 4a.

Seepage may be substantially minimized by utilizing a piston structurepermitting a hydraulic piston ring action, such as illustrated in Fig.'7. Here, the piston 5f is provided with an axial boring 30' which isintersected by one or more I or X transverse borings 3|'. of I or X boreends is enscribed by annular recess 33'. Before use, i. e., before thepiston is in-4 serted in its cylinder, the ducts are filled with asubstance of higher viscosity than the plastic 5c and preferablyinsoluble therein.

For linear hydraulic power-transfer, the plastic must be substantiallyincompressible. When not so, the power factor decreases, the lagincreases, and an unsymmetric cycle results. Such defects may bepractically overcome by suitably decreasing the length of the chambercontaining the plastic.

Due to the ease of transmitting power in any direction hydraulically,very compact body sections and cylinder heads may be designed. Fig. 8illustrates one such design. In this Fig. 8, the closure member lt forthe cup '2 has the piston Each set bore 34 transverse to diaphragmmovement. In bore 34 is the piston 5x having a thrust member or shaft 6'secured thereto and extending through and guided in a sleeve nut 24'..vAs in Fig. 1, the movement of the piston 5x is here opposed by spring Ilpositioned between piston 5x and nut 24', the piston being actuated byplastic material 5' moved by the diaphragm 4 or 4s4 (not shown) as inFigs. 3 and 6.

Various modifications and alternate combination of parts described willreadily occur to those skilled in the art without departing from thespirit and scope of this invention as herewith illustrated anddescribed. f

What I claim and desire to secure by Letters Patent is:-

1. In a thermostat, a container having a movable wall and acommunicating elongated hollow extension, and a mass of fusiblecrystalline material in said container and said extension such that thema'ss of material when in completely fused state will upon subjection tocrystallization temperature crystallize initially in said extensionthereby providing seed crystals for the remainder of said mass.

2. In a thermostat, a cup-like container having a movable wall closingand sealing its open side, an elongated hollow. tubular extensionprojecting from and having one end opening into said container, theother end of said extension being closed and sealed, and a mass offusible crystalline material in said container and said extension suchthat the mass of material when in completely fused state will uponsubjection to crystallization temperature crystallize initially in saidextension thereby providing seed crystals for the remainder of saidmass.

3. In a thermostat, a heat-transmitting container having a movable walland a communicating elongated hollow extension, heat-transmitting meanswithin said container and in heat conducting relation to a wall of saidcontainer, and a mass of fusible crystalline material in said containerin intimate heat conducting relation to said means and in said extensionsuch that the mass of material when in completely fused state will uponsubjection to crystallization temperature crystallize initially in saidextension thereby providing seed crystals for the remainder of saidmass.

4. A control device comprising an apertured supporting member operableto close a partition aperture, a container carried by said member, ahollow body member extending through the supporting member aperture andhaving an opening communicating with said container, a movable wallinterposed between and separating the interiors of said container andsaid body member, a piston in said body member and movable in responseto movement of said wall, a fusible crystalline material in saidcontainer, said material being expansible on fusing and acting uponfusing to move said wall, a tubular member having an open end openinginto said container and having its other end closed and sealed, saidtubular member extending through said supporting member and containingsaid fusible crystalline material, such that upon fusing of the materialin said container, the material in the closed end portion of saidtubular member will remain in crystal state.

5. In an apparatus of the character described, a partition separatingregions of different sensible heat, a hollow body member extendingthrough said partition, a container in the region of higher heat andcommunicating with said body member, a piston reciprocal in said bodymember and operable to actuate means in the region of lesser heat, aplastic power-transmitting medium in said body member, a fusiblecrystalline material in said container and expanslble upon fusing, amovable wall operable -to transmit the expanslble force of said materialto said plastic medium, and a tubu. lar member extending through saidpartition and having one end opening into said container and having itsother end closed and sealed and positioned in said region of lesserheat, said tubular member containing said fusible material.

6. In a thermostat, a container, an expanslble fusible crystallinematerial in said container, a porous filter plate in said container andmaintaining said material in situ, a liquid medium in said container,and a movable wall member in said container and overlying said liquid,said liquid acting upon fusing of said material to transmit theexpansive force thereof through said filter `plate to said wall member.

7. In a thermostat, a container, an expanslble fusible crystallinematerial in said container, a porous bronze filter member in saidcontainer and maintaining said material in situ, a liquid medium in saidcontainer, and a movable wall member in said container and overlyingsaid liquid, said liquid acting upon fusing of said material to transmitthe expansive force thereof through said bronze filter member to saidwall member.

8. In a thermostat, a container, an expanslble fusible crystallinematerial in said container, a

porous siliceous filter member in said container and maintaining saidmaterial in situ, a liquid medium in said container, and a movable wallmember in said container and overlying said liquid, said liquid actingupon fusing of said material to transmit the expansive force thereofthrough said siliceous filter member to said wall member.

9. In a thermostat. a container having a hollow extension, fusiblecrystalline material in said container, and a phase-change medium insaid extension and in contact with said crystalline material.

10. In a thermostat, a container having a hollow extension, fusiblecrystalline material in said container, means in said container and inintimate contact with said material to enhance the rapidity of transferof temperature changes to which the container is subjected to andthroughout said material, and a phase-change medium in said extensionand in intimate contact with said material.

11. In an apparatus of the character described, a partition separatingregions oi different sensible heat, a container in the region of higherheat and having a hollow extension projecting through said partitioninto the region of lesser heat, a fusible crystalline material in saidcontainer and expansible on temperature change, means closing an openingin the container wall and movable by expansion of said material, and aphase-change medium in said extension.

SERGIUS VERNET.

